One of the world's most useful sources of energy is crude oil, derived from subterranean formations. When crude oil arrives at the earth's surface it is typically in the form of a water-and-oil mixture. That is, crude oil invariably has associated water that must be separated before the oil component can be efficiently refined into useful commercially acceptable products.
A common technique for improving the effectiveness of oil/water separation is by use of coalescence—that is a technique of joining together smaller into larger water droplets that are more readily separated from the mixture. As water droplet size increases, the dynamics of gravitational separation improve. One method of augmenting coalescence of water droplets is by subjecting the mixture to an electric field. Oil, being a non-polar fluid, acts as a dielectric and water droplets, being polar, when subjected to an electric field are coalesced. Coalescence is usually practiced by establishing an electric field between electrodes and passing an oil-in-water mixture through the electric field. Since water is slightly polar, water droplets become polarized by the electric field. Polarized droplets are attracted to each other and move into and coalesce with each other. Larger droplets tend to gravitate downwardly within the mixture and the oil, having portions of the water removed therefrom, tends to gravitate upwardly within the mixture.
However, most conventional oil-and-water separators are designed to treat feed streams with low velocities. As a result, they are only capable of treating low volumes and their overall capacity for separating mixed oil-and-water streams into water out-flux and dehydrated oil is limited. There is a need for a separation vessel that can treat higher volumes of mixed oil-and-water streams and effectively separate them into streams of water out-flux and dehydrated oil while minimizing rag volume, reducing the quantity of solids carried over to the dehydrated oil, and handling slugs of water coming through the feed stream.